JPH11168123A - Substrate for disposing conductive particle and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable readily and satisfactorily a joint to other substrates via conductive particles by a method, wherein the conductive particles are adhered to a specified position and disposed. SOLUTION: For adhering conductive adhesives of average particle size of 30 to 2,000 μm, this substrate for disposing conductive particles in which an adhesive layer having the longest part which is twice or less the diameter of the conductive particles is formed. The longest portion of the adhesive layer is set 0.1 to 1 times the diameter of the conductive particles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate such as a ball grid array (BGA), in which conductive fine particles are arranged, and the conductive fine particles are arranged for bonding with other substrates or elements such as semiconductor chips. Substrate, and using conductive fine particles,
The present invention relates to a method for arranging conductive fine particles used when bonding an arrangement substrate to another substrate or the like.

[0002]

2. Description of the Related Art When manufacturing an electronic device such as a liquid crystal display device, it is necessary to bond an element such as an integrated circuit (LSI) or a semiconductor chip to a substrate having electrodes such as a liquid crystal display panel. Conventionally, conductive bonding has been performed. As a material used for conductive bonding, for example,
Japanese Patent No. 61204 discloses a conductive adhesive sheet obtained by kneading a solder alloy and a plastic material,
JP-A-62-61396, JP-A-62-1611
No. 87 and Japanese Patent Application Laid-Open No. Sho 62-127194 disclose materials for conductively joining an electrode substrate and an element such as a semiconductor chip by using solder.

Japanese Patent Application Laid-Open No. Sho 62-41238 discloses a method of conducting conductive bonding using conductive fine particles. For example, Japanese Patent Application Laid-Open No. Sho 62-41238 discloses a conductive filling method in which a nickel alloy coating layer is provided on the surface of a copper core. A material is disclosed, and such a conductive filler is used as an adhesive in an organic polymer material or a paint. In addition to such a method, for example, a method has been proposed in which silver fine powder is mixed into an epoxy resin and conductive fine particles formed into particles are used.

However, it has been difficult for these methods to sufficiently reduce the electric resistance. In addition, at the time of conductive bonding, since an organic polymer material or the like is used as an adhesive, electrical connection is made by conductive fine particles, and mechanical connection is made by an organic polymer material or the like. When the electronic parts are bonded at a high temperature, the organic polymer material etc. thermally expands and the electrical connection becomes poor,
There were problems such as an increase in electric resistance.

[0005] As a conductive bonding method not using an adhesive such as an organic polymer material, a ball grid array (B) is currently used.
GA), flip chip bonding, and the like are performed, and solder particles are widely used as conductive fine particles. As a method of arranging the conductive fine particles on the substrate at the time of bonding using the conductive fine particles, a method of attracting and arranging the individual conductive fine particles by suction is used. However, there is a problem that a large-scale apparatus is required to implement this method.

[0006]

SUMMARY OF THE INVENTION In view of the above, the present invention is directed to a substrate such as a BGA in which conductive bonding is performed by conductive fine particles, wherein the substrate is connected to another substrate or semiconductor chip via conductive fine particles. An object of the present invention is to provide a substrate for arranging conductive fine particles that is devised so that bonding can be performed easily and well, and a method for arranging conductive fine particles on the substrate for arranging conductive fine particles. I do.

[0007]

According to the present invention, an average particle size of 30 is provided.
A substrate for disposing conductive fine particles on which an adhesive layer having a length equal to or less than twice the diameter of the conductive fine particles is formed at the longest portion in order to adhere the conductive fine particles of up to 2000 μm. Hereinafter, the present invention will be described in detail.

The substrate for arranging the conductive fine particles of the present invention (hereinafter simply referred to as “arrangement substrate”) has an average particle size of 30 to 30 μm.
A substrate of a type in which conductive fine particles of 2000 μm are adhered and conductive bonding between the placement substrate and another substrate or an element such as a semiconductor chip (hereinafter, referred to as “other substrate”) is performed through the conductive fine particles. It is.

The arrangement substrate is not particularly limited.
For example, a flip-chip substrate, a BGA, or the like can be given. The average particle size of the conductive fine particles is 30 to 2000 μm.

When the average particle diameter of the conductive fine particles is less than 30 μm, the conductive fine particles are too small, so that there is a possibility that the conductive fine particles may be arranged in places other than the adhesive layer due to the influence of electrostatic attraction and the like. When the average particle size exceeds 2,000 μm, the conductive fine particles are sufficiently large, so that the conductive fine particles can be arranged without forming the adhesive layer. Therefore, the average particle diameter is limited to the above range.

The conductive fine particles are usually preferably spherical fine particles having an aspect ratio of less than 1.2. When the aspect ratio exceeds 1.2, the shape of the conductive fine particles deviates greatly from the sphere, so that when the conductive fine particles are disposed on the placement substrate, the conductive fine particles disposed on the placement substrate The height of the substrate is not constant, and it is difficult to satisfactorily perform conductive bonding with another substrate or the like, and connection failure is likely to occur. Examples of the conductive fine particles include a solder ball and the like.

In the placement substrate of the present invention, the longest portion has an adhesive layer having a length of not more than twice the diameter of the conductive fine particles, and the conductive fine particles are adhered to the adhesive layer. Is arranged according to. The shape of the adhesive layer to be formed is not particularly limited, and examples thereof include a shape such as a circle, an ellipse, and a rectangle. At least the longest portion of the adhesive layer has a length not more than twice the diameter of the conductive fine particles. Must be formed. In addition, among the above shapes, a circle is preferable.

When the length of the longest portion of the adhesive layer exceeds twice the diameter of the conductive fine particles, there is a high possibility that two or more conductive fine particles are arranged in the adhesive layer. Limited to range. Preferably, it is 0.1 to 1 times the longest part of the diameter of the conductive fine particles. The adhesive layer is formed on the electrode on the surface of the placement substrate, and ultimately,
The adhesive layer disappears due to heat or the like, is removed, and the conductive particles and the electrode are conductively joined,
Connection with another substrate or the like is achieved.

Therefore, the thickness of the adhesive layer is preferably as thin as possible provided that the adhesive force of the adhesive layer is maintained. Further, it is preferable that a concave portion is formed in the electrode so that the conductive fine particles are easily stopped at a portion where the adhesive layer is formed.

The adhesive used to form the adhesive layer is not particularly limited, and examples thereof include an ethylene / vinyl acetate copolymer, an ethylene / acrylate copolymer, polymethyl (meth) acrylate, and polyethyl (meth) acrylate. ) (Meth) acrylate polymers or copolymers such as acrylate and polybutyl (meth) acrylate; polystyrene, styrene / acrylate copolymer, SB type styrene / butadiene block copolymer, SBS type styrene / butadiene block copolymer Coalescence, other vinyl polymers or copolymers, and resins such as epoxy resins, phenolic resins, and melamine resins. As the adhesive, the polymer, the copolymer, or a mixture of the resin and cream solder may be used.

Among the above-mentioned adhesives, they have high tackiness and are non-volatile at room temperature, but volatilize and disappear due to decomposition or the like at a high temperature of about several hundred degrees centigrade, and hinder the connection between the conductive fine particles and the electrodes. Those that do not are preferred. Also, the adhesive layer
A thin layer is preferred so that it will easily decompose and disappear on heating.

In the adhesive layer, a substance other than the conductive fine particles easily adheres, and therefore, the connection between the conductive fine particles and the electrode is easily hindered. Therefore, the surface of the mounting substrate is covered with a protective film. It is preferable that the protective film is peeled off immediately before the conductive fine particles are bonded, and the conductive fine particles are bonded.

According to the substrate for disposing conductive fine particles of the present invention, in order to adhere the conductive fine particles having an average particle diameter of 30 to 2000 μm, the longest portion has a length of twice or less the diameter of the conductive fine particles. Since the adhesive layer is formed, the conductive fine particles can be easily adhered to each of the adhesive layers one by one by using the above-mentioned arrangement substrate. It can be easily and satisfactorily joined to another substrate or the like.

According to a second aspect of the present invention, an adhesive layer having a longest portion having a length equal to or less than twice the diameter of the conductive fine particles is formed on a substrate for disposing conductive fine particles. Diameter 3
This is a method of arranging conductive fine particles for bonding conductive fine particles of 0 to 2000 μm.

In the method for arranging conductive fine particles according to the second aspect of the present invention, an adhesive layer is formed on an electrode of the arranging substrate or on a portion including the electrode by using the substrate for arranging the conductive fine particles. The conductive fine particles, the shape of the adhesive layer, and the like have already been described in detail in the section of the substrate for disposing conductive fine particles according to the first embodiment of the present invention.

As described above, after the adhesive layer is formed on the disposing substrate, until the conductive fine particles are adhered to the adhesive layer, the adhesion of other substances to the adhesive layer is prevented. Preferably, the arrangement substrate is covered with a protection film, and the protection film is preferably peeled off immediately before the conductive fine particles are adhered.

The method for adhering the conductive fine particles to the adhesive layer is not particularly limited. For example, after a large number of conductive fine particles are scattered on the disposing substrate and gently vibrated, the conductive fine particles are not adhered to the adhesive layer. A method of moving the conductive fine particles to the adhesive layer and bonding the conductive fine particles to the adhesive layer can be used.

In the case where concave portions are formed in the portions where the electrodes are formed, the conductive fine particles enter these concave portions by applying vibration and stop there. It becomes even easier.

Thereafter, the placement substrate to which the conductive fine particles are adhered is overlapped with another substrate or the like on which a lead electrode or the like is formed. At this time, it is necessary to overlap the conductive particles so that the conductive fine particles come into contact with the respective electrodes.

Thereafter, by heating the placement substrate and the like, the resin and the like of the adhesive layer are decomposed and eliminated, and the conductive fine particles, such as solder balls, are usually reflowed so that the placement substrate and other substrates are reflowed. To join them.

According to the method for arranging conductive fine particles of the second aspect of the present invention, the adhesive layer having the longest portion having a length not more than twice the diameter of the conductive fine particles is formed on the substrate for arranging the conductive fine particles. Then, since a method of bonding conductive fine particles having an average particle diameter of 30 to 2000 μm to the adhesive layer is adopted, the conductive fine particles can be easily bonded one by one to each of the adhesive layers. When joining substrates,
By removing the adhesive layer by heating or the like, bonding with another substrate or the like via the conductive fine particles can be easily and favorably performed.

[0027]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 An electrode having a hole diameter of half the diameter of a solder ball and an interval between adjacent electrodes being twice the diameter of the solder ball is vertically 10 mm long.
An acrylic adhesive was applied in a size of 600 μm in diameter to individual holes on 10 BGA chips arranged side by side so that the center of the holes was at the center of the hole.

Next, on this BGA chip, a diameter of 600
After spraying the solder ball of μm, the BGA chip was vibrated. As a result, the solder ball was arranged in all the holes of the BGA chip, and the solder ball was not found elsewhere.

The solder ball having been subjected to the above treatment was superimposed on a substrate provided with an extraction electrode, temporarily fixed with a gap material of 300 μm inserted around the solder ball, and joined while heating to 300 ° C. Thereafter, a test of the conduction state and the like of both substrates was performed. As a result, the conduction state of both substrates was good, and no short circuit between the electrodes was observed.

Example 2 A solder ball was placed on a BGA chip in the same manner as in Example 1 except that the adhesive was applied so that the diameter of the adhesive layer became 900 μm, and the BGA chip and the lead electrode were connected. After bonding with the provided substrate, a conduction test and the like were similarly performed.

When the conductive fine particles are sprayed on the BGA chip, the solder balls are arranged in all the holes on the BGA chip, and there is a portion where two solder balls ride on one adhesive layer. However, it was properly positioned by a light air purge, and no other solder balls were found. The connection state between the two substrates after bonding was good, and no short circuit between adjacent electrodes was observed.

Example 3 A solder ball was placed on a BGA chip in the same manner as in Example 1 except that the adhesive was applied so that the diameter of the adhesive layer became 50 μm. After bonding with the provided substrate, a conduction test and the like were similarly performed.

When the conductive fine particles were sprayed on the BGA chip, the solder balls were arranged in the holes on the BGA chip, and although there were some portions where the solder balls were missing,
After the solder balls were sprayed again, the BGA chip was vibrated. As a result, the solder balls were arranged in all the holes on the BGA chip, and no other solder balls were found. The connection state between the two substrates after bonding was good, and no short circuit between adjacent electrodes was observed.

Example 4 The shape of the adhesive layer was rectangular with a width of 50 μm and a length of 400 μm. When the solder balls were to be placed, the BGA chip was put in a box to accommodate the solder balls, and was stirred slightly. Take it out and vibrate the BGA chip,
After joining the BGA chip and the substrate provided with the extraction electrodes in the same manner as in Example 1, a continuity test and the like were conducted in the same manner.

By the above-mentioned processing, solder balls were arranged in all the holes on the BGA chip, and no solder balls were found elsewhere. The connection state between the two substrates after bonding was good, and no short circuit between adjacent electrodes was observed.

Example 5 The diameter of the adhesive layer was 100 μm and the diameter of the solder ball was 1
Except that the thickness was set to 00 μm, solder balls were arranged on the BGA chip in the same manner as in Example 1, and after joining the BGA chip and the substrate provided with the lead electrodes, a conduction test and the like were performed in the same manner.

When the conductive fine particles were sprayed on the BGA chip, the solder balls were arranged in all the holes on the BGA chip, and no other solder balls were found. The connection state between the two substrates after bonding was good, and no short circuit between adjacent electrodes was observed.

Example 6 A solder ball was arranged on a BGA chip in the same manner as in Example 1 except that the diameter of the solder ball was 1500 μm, and the BGA chip was bonded to a substrate provided with extraction electrodes. Thereafter, a continuity test and the like were similarly performed.

When the conductive fine particles were sprayed on the BGA chip, the solder balls were arranged in all the holes on the BGA chip, and no other solder balls were found. The connection state between the two substrates after bonding was good, and no short circuit between adjacent electrodes was observed.

In Examples 1 to 6, when the adhesive layer was formed on the BGA chip and left as it was, when the solder balls were arranged due to the influence of dust and the like, a decrease in the adhesive strength was observed. In some cases, after the solder balls were placed, there was a phenomenon in which the solder balls were missing.However, when the BGA chip was covered with a polyethylene protection film and peeled immediately before placing the solder balls, the above phenomenon was observed. Did not occur.

Example 7 An epoxy-based hot melt adhesive was used in place of the acrylic adhesive, and the size of the adhesive layer was 1000 μm in diameter.
Except that the solder balls were heated to 100 ° C., the solder balls were arranged on the BGA chip in the same manner as in Example 6, and after joining the BGA chip and the substrate provided with the extraction electrodes, A continuity test and the like were performed.

When the conductive fine particles were sprayed on the BGA chip, the solder balls were arranged in all the holes on the BGA chip, and no other solder balls were found. The connection state between the two substrates after bonding was good, and no short circuit between adjacent electrodes was observed.

Comparative Example 1 Example 1 was repeated except that the diameter of the adhesive layer was 1300 μm.
The solder balls were arranged on the BGA chip in the same manner as described above, and the BGA chip was joined to the substrate provided with the lead-out electrodes.

Although all the solder balls are arranged on the BGA chip, there is a portion where two solder balls are adhered on one adhesive layer.
The portion where the two solder balls were bonded on one adhesive layer did not completely disappear. Although the connection state between the two substrates after the bonding was good, a short circuit was observed between the adjacent electrodes.

Comparative Example 2 The procedure of Example 1 was repeated except that no adhesive layer was formed.
After placing the solder balls on the GA chip and joining the BGA chip and the board with the lead electrodes,
Similarly, a continuity test and the like were performed.

No solder balls were placed in most of the holes on the BGA chip. No short circuit was observed between the adjacent electrodes, but a number of unconnected points were observed on both substrates after bonding.

COMPARATIVE EXAMPLE 3 Except that the adhesive layer was not formed and the solder balls were placed one by one in the holes on the BGA chip using a suction device.
Using the same arrangement substrate as in Example 1, a BGA chip and a substrate provided with a lead-out electrode were joined in the same manner as in Example 1, and then a continuity test and the like were similarly performed.

Although solder balls were arranged in all the holes on the BGA chip and no other solder balls were seen, a large-scale suction device had to be used and the operation was complicated. Was. The connection between the two substrates after bonding was good, and no short circuit between adjacent electrodes was observed.

Comparative Example 4 The diameter of the adhesive layer was 20 μm, and the diameter of the solder ball was 20 μm.
A solder ball was placed on a BGA chip in the same manner as in Example 1 except that the thickness was set to μm, and after joining the BGA chip and a substrate provided with a lead electrode, a conduction test and the like were performed in the same manner.

When the conductive fine particles were sprayed on the BGA chip, the solder balls were arranged in all the holes on the BGA chip. However, two solder balls were placed near the adhesive layer, which is considered to be caused by electrostatic attraction. There were portions to which the solder balls adhered, and solder balls were also found in portions other than the holes. In addition, the connection state between the two substrates after bonding was good, but short-circuiting between adjacent electrodes was partially observed.

Comparative Example 5 A solder ball was arranged on a BGA chip in the same manner as in Example 1, except that the diameter of the adhesive layer was set to 2000 μm and the diameter of the solder ball was set to 3000 μm. After joining with the substrate, a conduction test and the like were similarly performed.

When the conductive fine particles were sprayed on the BGA chip, the solder balls were arranged in all the holes on the BGA chip, and no solder balls were found in other portions. The connection between the two substrates was good, and no short circuit between adjacent electrodes was observed. However, in this case, since the solder balls were large even without the adhesive layer, the solder balls could be sufficiently arranged in all the holes by the above-mentioned manual operation, and similar results could be obtained.

[0054]

The substrate for disposing conductive fine particles of the present invention is
With the above-described configuration, the conductive fine particles can be easily adhered one by one to each of the adhesive layers, whereby the bonding with another substrate or the like via the conductive fine particles can be easily and preferably performed. Can be done. In addition, since the method for arranging conductive fine particles of the present invention has the above-described configuration, the conductive fine particles can be easily bonded one by one to each of the adhesive layers. By removing the adhesive layer by the method described above, the bonding with another substrate or the like via the conductive fine particles can be easily and satisfactorily performed.

Claims (6)

[Claims] An adhesive layer having a longest portion having a length not more than twice the diameter of the conductive fine particles is formed for bonding conductive fine particles having an average particle size of 30 to 2000 μm. Substrate for disposing conductive fine particles. 2. The substrate according to claim 1, wherein the longest portion of the adhesive layer has a diameter of 0.1 to 1 times the diameter of the conductive fine particles. 3. The method according to claim 1, wherein the adhesive layer is covered with a protection film for protecting the adhesive layer.
Or a substrate for disposing conductive fine particles according to 2. 4. After forming an adhesive layer having a length of not more than twice the diameter of the conductive fine particles on the substrate for disposing conductive fine particles, the adhesive layer has an average particle size of 30 to 200
A method for arranging conductive fine particles, which comprises bonding the conductive fine particles of 0 μm. 5. The method for arranging conductive fine particles according to claim 4, wherein the longest part of the adhesive layer has a diameter of 0.1 to 1 times the diameter of the conductive fine particles. 6. The method according to claim 4, wherein the conductive film is adhered to the adhesive layer after the protective film is peeled off from the mounting substrate covered with the protective film for protecting the adhesive layer. Or the method for arranging conductive fine particles according to 5.